<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1, user-scalable=no">
    <meta http-equiv="X-UA-Compatible" content="ie=edge,chrome=1">
    <meta name="author" content="陈嘉乐">
    <title></title>
    <style>
        *{
            box-sizing: border-box;
        }
ul{
    width: 700px;
    margin: 200px auto;
    padding: 0;
    display: flex;
    position: relative;
    margin-left: 800px;
}
li{
    list-style: none;
}
li>a>img{
    width: 400px;
    height: 300px;
    position: absolute;
    left: 0;
    top: 0;
}
</style>
</head>
<ul>
    <li><a href="href#"> <img src="./img/1_1.jpg" alt="#"></a></li>
    <li><a href="href#"><img src="./img/1_2.jpg" alt="#"></a></li>
     <li><a href="href#"><img src="./img/2_1.jpg" alt="#"></a></li>
      <li><a href="href#"><img src="./img/2_2.jpg" alt="#"></a></li>
</ul>


     <script src="./jquery.js"></script>
</body>
</html>
<script>
$(function(){
$('ul li:not(:first)').css('display','none');
var bb = $('ul li:last');
var aa = $('ul li:first');
setInterval(function(){
  if(bb.is(':visible')){
      aa.fadeIn(1000).addClass('in');
      bb.hide();
  }else{
      $('ul li:visible').addClass('in');
      $('ul li.in').next().fadeIn(500);
      $('ul li.in').fadeOut(1000).removeClass('in');
  }
},1000);
});

</script>